We talked to PayPal about this. It is possible to have a merchant account accept more than $10k transactions. In order to do that you have to contact PayPal and go through a special process to get approval.
Because of that, we plan to remove the $9999 restriction from our authoring UI in our mid-May release. Until then the only work around is to use a "user inputted" price type instead of a fixed type. The donor would just type in an amount they want to donate. In that case we do not block entry of larger amounts. PayPal will determine if that amount is allowed during checkout.
Hope this helps.